Ventilation/HVAC systems for buildings and other enclosures are well known in the art. A core component of many ventilation systems is the need to regulate the influx of outside ambient air. One aspect of this regulation is the desired ability to prevent particulate matter from entering the ventilation system along with the outside ambient air, and louver assemblies have therefore been traditionally utilized to help control the flow of ambient air and any entrained particulate matter.
Recent natural disasters and code modifications have placed larger burdens on the performance of louver assemblies that are integrated into various ventilation systems. In particular, recent code modifications have centered on reducing or eliminating the amount of rain water (i.e., water droplets) that are permitted to pass through the louver assembly and into the ventilation system as a whole.
On this issue, louvers that attempt to separate water and other particles from air flowing into buildings are generally known in the art. As exemplified by U.S. Pat. No. 5,839,244, hereby incorporated by reference, such prior art louvers typically include a plurality of curved, spaced blades that define a plurality of spaced, serpentine-shaped air passageways therebetween. The air passageways direct air from the exterior of the building to the interior of the building for air conditioning of the building.
When air passes into the building through the air passageways, the water particles in the air, which are heavier than the gas molecules in the air, cannot turn through the serpentine-shaped contours in the air passageways. The water molecules therefore strike the walls of the blades, agglomerate into drops and flow by gravity down the blades and out of the louvers.
However, buildings in areas of the world that are especially prone to hurricanes face much tougher problems with the design of louvers. In such hurricane zones, wind-driven rain may sometimes pass through the louver and into the building. In other situations, rain may accumulate at the bottom of a louver and be pushed through the louver and into the building by a constant and steady airflow. In addition, hurricanes and tornadoes often pick up debris which may be propelled by strong winds into the louver. Depending on the size and speed of the debris, such debris may damage the louver and cause the localized yielding of welds, compromising the integrity and functionality of the louver. Moreover, increased wind speed and thus increased airflow often leads to blade flutter or “chatter,” which is undesirable. In hurricane zones, such as Miami-Dade County in the state of Florida, stringent building codes have recently been adopted which require louvers, dampers and the like to pass stringent tests for wind and wind-driven rain resistance. Additional building code provisions often require such louvers to pass missile impact, static load and cyclic load tests at varying speeds, pressures and cycles.
Unfortunately, known louvers are simply not designed to withstand missile impacts of the size and speed often generated by strong storms such as hurricanes and tornadoes. Moreover, known louver assemblies have a substantial amount of blade “chatter” when subject to high winds or large airflow volumes.
Therefore, in order to achieve a sufficient wind and wind-driven rain resistance, known louvers often employ a separate damper assembly behind the louver to block off water penetration. However, the closing of the damper to block off water penetration also blocks the flow of air into the building, which disqualifies such louver/damper systems from use in hurricane zones or other areas that frequently see high winds and large amounts of rain.
Known louvers capable of expelling water are generally of two types. The first type is a louver that employs separate gutters or down spouts or other drainage systems for carrying the removed water away from the louver and out of the building. This type of louver is undesirable because a separate drainage system must be installed to carry the water out of the building. The second type of louver utilizes drain holes to expel water. In these louvers, there is an orifice or nozzle pressure present at these drain holes as well as in between each blade. However, until enough water builds up to overcome the orifice pressure and drain via the drain holes, the water built up inside the louver is carried though the louver and into the building with the airflow. An example of this type of louver is shown by U.S. Pat. No. 5,839,244 (Paul A. Johnson et al.).